EP 197 496 A discloses a process for molding and coating an article (herein a substrate) in the mold. The molding of the substrate is carried out between two separable sections of the mold with a mold cavity lying in between, until the substrate has at least partly cured. When the substrate has cured to the extent that its surface has formed a skin which is receptive to the coating, the coating is injected into the mold cavity. The coating is injected in under a pressure which is considerably above the pressure which prevailed in the mold cavity immediately before the injection. During the injection, the sections of the mold are kept in a closed position under pressure without substantial Withdrawal of the sections. The coating is thereby substantially forced over the entire surface of the substrate and compressed. According to EP 197 496 A, molding of the substrate is carried out by means of injection compression molding. Various disadvantages, e.g. lengthening of the cycle time, which are associated with opening and closing of the mold before injection of the coating were said to be avoided with the process according to EP 197 496 A. According to EP 197 496 A, by injecting the coating under a pressure which is greater than the curing pressure, the opening and closing can be by-passed. Disadvantages of the process described in EP 197 496 A arise from the fact that substrate production and substrate coating take place sequentially in one cavity. Various process parameters for the two process steps, such as e.g. wall thickness of the coating or mold surface temperature are therefore restricted.
DE 43 16 154 A describes a process for coating an interior finishing component with a crosslinkable curing resin or lacquer. In this process, the interior finishing component is laid in a defined position into a mold, in order for a coating to be applied to the surface of the interior finishing component in the manner of an injection molding or pressure diecasting operation. The resin or the lacquer is applied in the required total thickness in the closed mold in a single working step. During the entire curing time, a pressure which remains constant with respect to time is exerted on the resin or lacquer, which is initially liquid and then sets in the mold, in spite of a shrinkage due to the setting. In this context, the pressure is chosen such that any air present is dissolved in the liquid resin or lacquer. In the process according to DE 43 16 154 A, a ready-made interior finishing component is laid into the mold for the coating operation. The interior finishing component is accordingly produced independently of its coating. During coating, the internal pressure in the mold is maintained, in spite of the shrinkage, by driving in the ram of the mold. The high internal pressure in the mold is said to have the effect that air remains dissolved during the curing and thus does not adversely influence the quality of the coating. The external production of the interior finishing component to be coated by injection is a disadvantage, since this in particular increases the expenditure on apparatus for the process. The production costs are therefore considerably higher.
EP 934 808 A discloses a process for in mold coating, which comprises, in a first step, the production of a shaped article in the mold from a synthetic resin by an injection molding process, an injection compression molding process or an injection press-molding process. This is effected by applying a clamping pressure to a mold, which includes a fixed mold half and a movable mold half. In a second step, the clamping pressure is reduced or the fixed and movable mold sections are moved apart, before a coating material is injected into the mold between an inner surface of the mold and a surface of the shaped article in a further step. Clamping of the mold after the injection of the coating material is carried out under certain clamping pressures which can be varied in multiple stages, with certain clamping pressure transition periods. The two steps of the process according to EP 934 808 A, the molding of the shaped article and the coating of the shaped article, are carried out in one cavity, curing of the coating taking place under a specific pressure profile. Since in this process also the individual steps are carried out in one cavity, the same disadvantages as for the process according to EP 197 496 A apply.
US 2003/0197307 A discloses a process for injection molding of a molding and subsequent coating with a thermosetting lacquer layer. The injection molding and subsequent coating take place in two separate mold cavities. According to US 2003/0197307 A, a thermosetting composition which substantially comprises no readily volatile components is employed for the coating.
The object of the present invention is to provide a process for molding a substrate and coating with a lacquer, which does not have the abovementioned disadvantages of the prior art. The lacquer coating in particular may be applied uniformly and in a faultless quality, independently of its thickness.